Like I said, the audience doesn't need to know Shocker's entire backstory. Just introduce him quickly over the span of a minute or so in a news report of an inner monologue and keep it moving. The beginning of the movie didn't really have anything to do with the plot, aside from being another lesson of great power and responsibility(which still could have been accomplished by having Shocker be the reason that Peter was late).

The audience doesn't need to know things like background or explanations when it comes to cartoons and comics, because we accept the internal logic of the world established. In the movie world, there is no indication whatsoever that the city is inhabited by superpowered beings- and it wasn't Raimi's intent to try to establish such a thing.

The beginning had everything to do with the plot. Peter's life is already so busy and stressful and his Spider-Man persona adds to that. Having Spider-Man saving a child accomplishes the same thing that bringing in a new super-being (WTF) would accomplish except for being much more economical in terms of story telling and much less a bit of fan-wankery.